I would like to add my two cents to the
eyepiece comments ... some time ago a very famous optician spent the night
at my house... he had with him various eyepieces... among them a Nagler and
also a Pentax XL... he put the eyepieces on their ends with the end caps on
and aimed the exit lenses to the open blue sky. The Nagler appeared to have
a soft glow going on inside it... the Pentax XL looked like a black hole.
The explanation that I got was as follows:
Although Naglers are
claimed to be "fully multi-coated" the coatings are all similar,
ie, they are the average of all the index of refractions of the lens
elements. As the light goes down the Nagler from the open sky, a small
amount of it is bounced back as it reflects from each of the glass
elements.
The Pentax XL is
multi-coated the correct way... each coating is carefully applied to the
INDIVIDUAL index of refraction of EACH glass element... it looks like a
black hole because all the light is passing down the eyepiece and hitting
the black end cap, rather than reflecting bit by bit from the lens
elements.
The end result is an
eyepiece that passes all the light and has the highest level of contrast...
they also happen to have 20mm of eye relief and wonderful rubber eyeguards
that will not scratch glasses if you need to wear them like I do for
astigmatism. The only downside is you don't get the extreme wide angle
effect of a Nagler... but you can only look in one place at a time
anyway...
My two cents for what
it's worth on high end eyepieces...
Tony